A robust immersed boundary-lattice Boltzmann method(IB-LBM)is proposed to simulate fluid-structure interaction(FSI)problems in this work.Compared with the conventional IB-LBM,the current method employs the fractional ...A robust immersed boundary-lattice Boltzmann method(IB-LBM)is proposed to simulate fluid-structure interaction(FSI)problems in this work.Compared with the conventional IB-LBM,the current method employs the fractional step technique to solve the lattice Boltzmann equation(LBE)with a forcing term.Consequently,the non-physical oscillation of body force calculation,which is frequently encountered in the traditional IB-LBM,is suppressed greatly.It is of importance for the simulation of FSI problems.In the meanwhile,the no-slip boundary condition is strictly satisfied by using the velocity correction scheme.Moreover,based on the relationship between the velocity correction and forcing term,the boundary force can be calculated accurately and easily.A few test cases are first performed to validate the current method.Subsequently,a series of FSI problems,including the vortex-induced vibration of a circular cylinder,an elastic filament flapping in the wake of a fixed cylinder and sedimentation of particles,are simulated.Based on the good agreement between the current results and those in the literature,it is demonstrated that the proposed IB-LBMhas the capability to handle various FSI problems effectively.展开更多
The existence of the heaving plates can improve the heaving motion performance of an offshore structure significantly by providing both extra added mass and damping.In the current research,numerical investigation is c...The existence of the heaving plates can improve the heaving motion performance of an offshore structure significantly by providing both extra added mass and damping.In the current research,numerical investigation is carried out on the hydrodynamic characteristics of both isolated square heaving plate and double square heaving plates with opening by an immersed boundary-lattice Boltzmann method.The effects on hydrodynamic performance of plates due to Keulegan-Carpenter(KC)number,frequency number,opening ratio,opening distribution and spacing of plates are examined.It is found that the heaving plates with optimized opening ratio can provide additional damping compared with the plates without opening.Better hydrodynamic characteristics of double plates can be obtained with the increase of plate spacing.展开更多
The ground effect on insect hovering is investigated using an immersed boundary-lattice Boltzmann method to solve the two-dimensional incompressible Navier-Stokes equations. A virtual model of an elliptic foil with os...The ground effect on insect hovering is investigated using an immersed boundary-lattice Boltzmann method to solve the two-dimensional incompressible Navier-Stokes equations. A virtual model of an elliptic foil with oscillating translation and rotation near a ground is used. The objective of this study is to deal with the ground effect on the unsteady forces and vortical structures and to get the physical insights in the relevant mechanisms. Two typical insect hovering modes, i.e., normal and dragonfly hovering mode, are examined. Systematic computations have been carried out for some parameters, and the ground effect on the unsteady forces and vortical structures is analyzed.展开更多
Fluid-structure-interaction problems are ubiquitous,complicated,and not yet well understood.In this paper we investigate the interaction of a leading rigid circular cylinder and a trailing compliant filament and analy...Fluid-structure-interaction problems are ubiquitous,complicated,and not yet well understood.In this paper we investigate the interaction of a leading rigid circular cylinder and a trailing compliant filament and analyze the dynamic responses of the filament in the wake of the cylinder.It is revealed that there exist two flapping states of the filament depending on the cylinder-filament separation distance and the relevant critical distance distinguishing the two states is associated with the Reynolds number and the filament length.It is also found that the drag coefficient of the cylinder is reduced but that of the filament may be increased or decreased depending on its length.Compared with a single filament in a uniform flow,the filament of the same mechanical properties flapping in the wake of the cylinder has a lower frequency and a greater amplitude.展开更多
基金J.W.acknowledges the support of the Natural Science Foundation of Jiangsu Province(Grant No.BK20130778)the National Natural Science Foundation of China(Grant No.11302104)N.Z.acknowledges the support of the National Program on Key Basic Research Project(Grant No.2014CB046201).This work is also supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘A robust immersed boundary-lattice Boltzmann method(IB-LBM)is proposed to simulate fluid-structure interaction(FSI)problems in this work.Compared with the conventional IB-LBM,the current method employs the fractional step technique to solve the lattice Boltzmann equation(LBE)with a forcing term.Consequently,the non-physical oscillation of body force calculation,which is frequently encountered in the traditional IB-LBM,is suppressed greatly.It is of importance for the simulation of FSI problems.In the meanwhile,the no-slip boundary condition is strictly satisfied by using the velocity correction scheme.Moreover,based on the relationship between the velocity correction and forcing term,the boundary force can be calculated accurately and easily.A few test cases are first performed to validate the current method.Subsequently,a series of FSI problems,including the vortex-induced vibration of a circular cylinder,an elastic filament flapping in the wake of a fixed cylinder and sedimentation of particles,are simulated.Based on the good agreement between the current results and those in the literature,it is demonstrated that the proposed IB-LBMhas the capability to handle various FSI problems effectively.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51490672 and 51879039)
文摘The existence of the heaving plates can improve the heaving motion performance of an offshore structure significantly by providing both extra added mass and damping.In the current research,numerical investigation is carried out on the hydrodynamic characteristics of both isolated square heaving plate and double square heaving plates with opening by an immersed boundary-lattice Boltzmann method.The effects on hydrodynamic performance of plates due to Keulegan-Carpenter(KC)number,frequency number,opening ratio,opening distribution and spacing of plates are examined.It is found that the heaving plates with optimized opening ratio can provide additional damping compared with the plates without opening.Better hydrodynamic characteristics of double plates can be obtained with the increase of plate spacing.
基金the National Natural Science Foundation of China (Grant No. 10332040)the Innovation Project of the Chinese Academy of SciencesProgram for Changjiang Scholars and Innovative Research Team in University.
文摘The ground effect on insect hovering is investigated using an immersed boundary-lattice Boltzmann method to solve the two-dimensional incompressible Navier-Stokes equations. A virtual model of an elliptic foil with oscillating translation and rotation near a ground is used. The objective of this study is to deal with the ground effect on the unsteady forces and vortical structures and to get the physical insights in the relevant mechanisms. Two typical insect hovering modes, i.e., normal and dragonfly hovering mode, are examined. Systematic computations have been carried out for some parameters, and the ground effect on the unsteady forces and vortical structures is analyzed.
基金the National Natural Science Foundation of China(Grant No.11372304)and the 111 Project(Grant No.B07033)。
文摘Fluid-structure-interaction problems are ubiquitous,complicated,and not yet well understood.In this paper we investigate the interaction of a leading rigid circular cylinder and a trailing compliant filament and analyze the dynamic responses of the filament in the wake of the cylinder.It is revealed that there exist two flapping states of the filament depending on the cylinder-filament separation distance and the relevant critical distance distinguishing the two states is associated with the Reynolds number and the filament length.It is also found that the drag coefficient of the cylinder is reduced but that of the filament may be increased or decreased depending on its length.Compared with a single filament in a uniform flow,the filament of the same mechanical properties flapping in the wake of the cylinder has a lower frequency and a greater amplitude.
